For Dell Laptop DC Power Charge Converter Adapter Cable Cord 7.4*5.0 to 4.5*3.0 mm Female (WHL #102)
Here’s something not to burn your house down with: DC power supply adapters.
My lighbox currently draws power from the 3D printer power supply, which does work, but has its limitations. Sure, I do have to move down the gantry to take photos in the first place, so the printer will be on anyways, but I am not able to run it during prints (time lapse?) due to power constraints. The build plate heater is 400W and only gets pulsed on-off (so no linear “oh 200W will do at the moment” regulation), and the power supply is a 500W unit from MeanWell. Meaning that when operating three 45W LED panels plus some conversion losses in addition, that 500W power supply won’t cut the mustard.
Luckily, the laptop industry is moving towards USB-C for supplying power, so the old barrel-style supplies are phased out. It will be more difficult to extract power from the new USB-C units in the future, but for now, the supply of old gear is plenty. So I bought a Dell / Alienware DA210PE1-00 AC for 7.29€ on German eBay (including AC cable and delivery), which is a fucking massive chungus of a power brick with 19.5V x 10.8A = 210W of available power, and a 7.4mm x 5.0mm barrel connector with center pin (encoding the amperage, like almost all manufacturers do).
I didn’t feel like snipping off the power cable for a fully fixed installation, so I went to AliExpress to find some kind of adapter that I can solder onto. I did buy the laptop DC-in jacks for Lenovo power supplies in the past, but no luck here – the only thing I could find was adapters to a different size of barrel connectors. So I got the cheapest – they’re all using the same images, so most likely they’re all the same, regardless of dollar amount spent on. I paid 1.65€ with “Choice” delivery, so free when reaching a total cart sum of 10€ at checkout.
So here’s the promo images of the thing:
Since the first thing I did was cutting off the other end, that length of cord and size of the other barrel was fine by me – YMMV.
“Big Mouth” probably sums it up perfectly.
However, cutting through the thing instantly revealed something: Wire strand size (yup, sorry, ripped the center pin clean off when removing all the plastic-y potting, that’s how sturdy the wires and solder joints are)
Yes, this is a very short adapter and even some 0.14mm² copper wire (which this isn’t far off) “only” has 125mΩ of resistance per meter, so voltage drop isn’t that much. But guys, this is an adapter for a 10.8A power supply – I don’t want an additional fuse in my DC lines, and I especially want no fire starter for when one of the few strands breaks with wear or the solder joints are crappy from the beginning.
Shown besides the adapter wiring in white is a 0.75mm² cable in blue and a 1.0mm² in black. I’d say the former is recommended for short strings of wiring, and the latter (somewhat unusual, 1.5mm² is more common) is better for wires of 1m+ in size. But that bit of (verified) copper they use in there…pathetic.
10.8 amps. Don’t burn down your house with one of those…
Last-minute “oh, and by the way” addition: In case your high current power supply won’t play nice with setups like mine, check their input capacitors. My DC-DC converter that ups the voltage from around 20V up to 40ish volts for the LED has a single 1000µF 63V cap on the input. The Dell DA210PE1 will go high impedance the very moment it sees that load connected after its own startup and will not exit that mode until the next power cycle. It works fine when connected right away, before the PSU sees any AC, but it won’t do when connected afterwards with zero charge in that cap (sometimes a bit of juice left did the job, that’s how I found out).
In my case I just replaced that very cap with a 100µF type of the same pin pitch (higher voltage, not really needed but convenient to do so). The PSU very likely has tons of output capacitance integrated already and it’s a pretty static setup with low buffering capabilities needed, so that’ll work for me. Now I can switch on and off the lighting as needed, without a power cycle of the PSU. No magic with the center coding pin needed.
